Geophysical and geological integration and interpretation of the northeast Thelon Basin, Nunavut

Abstract

<p>The northeast Thelon Basin, Nunavut, is a rapidly developing albeit poorly studied, frontier exploration domain for unconformity-associated uranium deposits. Critical criteria for unconformity –associated uranium deposit models are knowledge of the basement geology, fault history and depth to unconformity surface. This thesis sets forth to derive working geological and geophysical models for the northeast Thelon Basin through the implementation of integrated geophysical techniques.</p> <p>A physical rock property database is compiled defining average density and susceptibility values for key map units for integration into subsequent modelling iterations. Forward and inverse potential field modelling using these petrophysical with geological controls define the structure and geometry of the Shultz Lake intrusive complex and northeast Amer Belt, both of which are present below the Thelon sedimentary cover. Implementation of a new source edge detection technique estimates fault development and location within the basin. This provides a quantitative analysis of fault timing, identifying potentially reactivated faults which have an increased likelihood to serve as conduits to transport uranium-rich fluids and focus deposition. Corroborating the geophysical signatures on the aeromagnetic map with petrophysical properties and outcrop observations, a predictive geological map is developed for area beneath the sedimentary cover sequences. Inversion and interpretation of several discrete aeromagnetic anomalies provides local source depth estimates. Knowledge of fault locations is employed to delineate fault block boundaries. Interpreted geological model profiles include abrupt changes in sediment thickness with faults while abiding with the integrated source depth estimates. Integrating the results from a number of profiles provides a pseudo-3D rendition of the unconformity surface and its relationship to known faults. The geological-geophysical models which are presented herein incorporate all currently available data while providing a framework for the inclusion of future information as the knowledge gap for this remote region diminishes.</p>